Definition, Classification, Diagnosis and Differential Diagnosis of Diabetes Mellitus: Update 2023

Notice Of Update

The DDG clinical practice guidelines are updated regularly during the second half of the calendar year. Please ensure that you read and cite the respective current version.

Updates To Content Compared To The Previous Year’s Version

Change 1: Various changes in the section “Diagnostic approach for diagnosing diabetes” and “Pre-analytics of glucose measurement”. The new requirements for pre-analysis and analysis of glucose determination in accordance with the revised guideline of the German Medical Association for quality assurance of laboratory medical examinations (Rili-BAEK) are listed.

Reason: In May 2023, an updated version of the Rili-BAEK was published.

If applicable, supporting references: [13]

Change 2: The formulation on the reliability of HbA_1c in renal insufficiency has been adjusted.

Reason: Alignment with the clinical practice guideline “Nephropathy and Diabetes”.

If applicable, supporting references: [23]

Change 3: New section “Determination of ketone bodies”.

Reason: Measurement of ketone bodies is required in some clinical situations to determine the need for insulin therapy. Urine diagnostics, in which acetoacetate is measured, are delayed, and urine samples cannot be obtained easily at any time. On the other hand, measuring β-hydroxybutyrate in plasma or blood makes it possible to assess the risk of ketoacidosis more quickly.

If applicable, supporting references: [36] [37]

Change 4: Addition of the section “Differential diagnosis” to include a summarised description of the course of the development of type 1 or type 2 diabetes.

Reason: The differential diagnosis of type 1 and type 2 diabetes is summarised and thus easier for readers to understand.

Change 5: Removal of flow chart for differential diagnosis of type 1, type 2 diabetes and MODY

Reason: Due to the sometimes considerable fluctuations that can occur in the determination of C-peptide or autoantibodies depending on the laboratory and method, and due to the lack of standardisation in this context, the flow diagram has been removed. The diagnostic algorithm shown in this figure is still cited in the text, but it also points out the variability in the determination of C-peptide and autoantibodies.

Change 6: The “Outlook” section addresses the subtyping of type 1 and type 2 diabetes.

Reason: Subtyping is increasingly being discussed and is already being used in type 2 diabetes. A detailed analysis of the subtyping is still missing, so that no conclusive assessment is possible yet.

If applicable, supporting references: [64] [65]

Change 7: Brief discussion of diabetes diagnosis in clinics in the “Outlook” section.

Reason: There is a lack of systematic diabetes screening in clinics. The diagnostic algorithm is also not easily applicable. However, there is no national or international consensus on the glucose threshold above which a diabetes diagnosis is likely in inpatients. The additional measurement of HbA_1c may be useful in reducing the proportion of patients with undiagnosed diabetes.

^† First Authors: Stefan Pleus, Andrea Tytko

Publication History

Article published online:
20 February 2024

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